Coring device with controlled releasing



I April 7, 1970 w. TIRASPOLSKY ETAL 3,504,750

CORING DEVICE WITH CONTROLLED RELEASING Filed March 6, 1968 4 Sheets-Sheet l INVENTORS v/molmm mmmmk/ R066? Kuwaiti ATTORNEY p 7, 1970 w. T IRASPCLSKY E AL 3,504,750

- CURING DEVICE WITH CONTROLLED RELEASING 4 Sheets-Sheet 2 Filed March 6, 1968 INVENTORS WLHHMIQ flmsflmy R me RdllV/EKE yvss 00141.01

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ATTORNEY P 7, 1970 w. T'IRASPOLSKY' ETAL 3,504,750 002mm DEVICE WITH CONTROLLED RELEASING' 4 Sheets-Shet 5 Filed March 6, 1968 FIG.3 I

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ATTORNEY I I H Aprll 7, 1970 TIRA S PQLSKY ETA-L 3,504,750

' CURING DEVICE WITH QNTROLLED RELEASING Filed March s, 1968 4 Sheets-Sheet 4 i 57 4 C 11. 1s i y 19 FIG] MEN-mm BY f f, him; JW 9 52};

ATTORNEYJ United States Patent 3,504,750 CORING DEVICE WITH CONTROLLED RELEASING Wladimir Tiraspolsky, 69 Avenue Victor Cresson, 92 Issyles-Moulineaux, France; Roger Rouviere, Quartier Fontfiguiere, 13 Aix-en-Provence, France; and Yves Willm,

153 Avenue Henri Sellier, 92 Suresnes, France Filed Mar. 6, 1968, Ser. No. 711,095 Claims priority, applicatiggsFrance, Mar. 9, 1967,

rm. c1. E211) 9/20, /00

US. Cl. 175-244 19 Claims ABSTRACT OF THE DISCLUSURE Coring device with controlled releasing The present invention relates to a device for obtaining ground samples or cores, which is particularly suitable for exploratory underwater core-drilling.

One of the most serious diffic-nlties encountered during such coring operations is the necessity of elfecting successively drilling and coring runs when a core must be collected at a depth which is greater than the useful length of the coring device, with moreover the risk of the ground falling in or crumbling between two successive coring and drilling operations, such crumbling occurring when drilling unconsolidated strata and making impossib e any interpretation of subsequent samplings.

The main object of the invention is to obviate this difiiculty by providing a coring device capable of full hole drilling like a drilling tool down to the depth at which it is desired to collect a core and capable of being transformed into a coring device by remote control from the surface when this depth has been reached.

In other words, the invention providesa device which is capable during one and the same run to drill down to the selected depth and thereafter to collect a core exclusively from this depth.

This device allows to explore the successive strata of a great thickness of ground by successively coring one after the other all the ground levels, without the need for each coring operation of reintroducing the coring tool into the previously drilled hole.

In its application to underwater coring this device will therefor not require the positioning of a drill guide tubing between the bottom and the surface.

This object is achieved, according to the invention, with a coring device including a tubular body member terminated at its lower end by a drill crown or hit and internally housing a core barrel, means for making this core barrel solid in rotation with a driving mechanism and for connectng it with a source of flushing fluid under pressure, a lug housed inside said core barrel, releasable locking means for locking said plug at the lower part of said core barrel, the lower part of said plug being provided with ground cutting elements, said coring device being characterized in that said releasable locking means are adapted to be controlled through a plurality of elemental operations comprising at least a variation in the pressure of the flushing fluid.

Patented Apr. '7, 1970 These elemental operations may consist of a succession of pressure variations or of the association of at least a pressure variation with a variation in the speed of rotation of the coring device.

The invention will be described hereinafter more in detail with reference to some non limitative embodiments thereof illustrated by attached drawings wherein:

FIGURE 1 shows in axial section a first embodiment of the device according to the invention in which the plug is locked in the drilling position;

FIGURE 1A is a view in partial section along aa of FIGURE 1;

FIGURE 2 shows this device in its position for coring;

FIGURE 3 illustrates in partial view a second embodiment of the device according to the invention in its drilling position;

FIGURES 4 and 5 are detailed views of the releasab e locking means of the device according to FIGURE 3;

FIGURE 6 illustrates the releasing operation in the case of the device according to FIGURE 3;

FIGURE 7 shows the device according to FIGURE 3 in its position for coring.

The device according to the invention shown by FIG- URE 1 includes a tubular body member 1 which, in this embodiment, is constituted by an upper element 2 and a lower element 3 coupled by a connecting threading 4. The upper element is adapted for connection through the coupling threading 5 with means for rotating the tubular body member 1 around the axis thereof and for feeding said tubular body member with flushing fluid 'under pressure.

Said means may be constituted either by a string of rigid drill stems driven in rotation from the surface or by a bottom motor directly coupled with the device according to the invention and supplied with water and energy from the surface through a drill tubing.

The tubular body member 1 is terminated by a coring crown or hit 6 traversed by channels 7 which are used for the flushing of the periphery of the cutting area (only one of these channels can be seen on the drawmgs). A core-barrel 8 is located inside the tubular 'body member 1 (guide shoes or a crown 48 provided with channels for the passage of the flushing fluid provide for the centering of this core barrel), and includes a plug 9 housed with some clearance within this core barrel. This plug is provided with channels 29 allowing for flushing the central zone of the cutting area, in the position for drilling shown by FIGURE 1.

The plug is on its lower external wall 30 provided with ground cutting elements so as to work as a drill bit in the drilling position of the device.

The core barrel 8 is provided at its lower end with means for locking the plug 9 in its lower position.

In the illustrated embodiment these locking means include an assembly of metallic balls 10 housed inside peripheral apertures provided at the lower part of the core barrel, these balls being bored and strung on a metallic rmg 11.

In the position for drilling (FIGURES 1 and 1A) these balls make both the plug 9 and the core barrel 8 integral with the coring crown or bit 6, being simultaneously inserted in recesses 12 and in grooves 13, which are respectively provided in the external wall of the plug 9 and in the internal wall of the coring crown or bit 6.

The internal wall of the lower element 3 of the tubular body member 1 exhibits, at the level of the grooves 13, an upwardly flared shape as shown by FIGURE 2, thereby permitting to easily introduce the balls 10 into these grooves when the core barrel 8 is lowered and inversely to easily disengage these balls from these grooves during a change from the drilling position (FIG. 1) to the cor- 3 ing position (FIG. 2) by only a simple axial disp acement of the core barrel 8.

The core barrel 8 housed in the lower element 3 of the tubular body element 1 is connected with means providing for the resilient suspension of said element inside this tubular body member 1.

These means include a supporting rod 14 the upper part of which is integral with a piston 15 bearing on the spring 16 which is supported by a seat 17 integral with the tubular body member 1, this seat including channels 18 for the flushing fluid.

The seat 17 of the spring 16 is surmounted by sleeve 19 guiding the supporting rod 14.

A pin 20 makes this supporting rod solid in rotation with the tubular member 1 by limiting the movements of this rod to axial displacements.

The piston 15 is provided with rescesses 21 wherein are located balls 22. These recesses are inwardly and downwardly directed, from the periphery of the piston toward the axis thereof. The balls 22 moves apart from this axis under the action of the centrifugal force when the tubular body member 1 is rotated, thereby uncovering the apertures of the channels 23 for the passage of the flushing fluid through the piston 15. At the standstill the balls fall back toward the piston axis and obturate the apertures of the channels 23. These apertures being obturated, the actuation of the pump providing for the circulation of the flushing fluid causes a pressure rise which results in a strong hydraulic thrust on the piston 15 leading to a compression of the spring 16.

The piston 15 is located in a chamber 24 inside the upper element 2 of the tubular body member 1, this chamber having at its lower part a diameter just suflicient to provide for sliding of the piston 15. An annular sealing joint 25 surrounds the piston 15.

The upper part of the chamber 24 has a widened part with a diameter which permits the flushing fluid to flow around the piston 15 when the latter is in its upper position corresponding to coring (position shown by FIG. 2).

The core-barrel 8 is surmounted by a head 26 connected with the upper part of this core-barrel through a threading 27.

This head includes channels 28 providing for the passage of the flushing fluid through the core-barrel and therefrom to the channels 29 of the plug 9, toward the central part of the cutting area in the drilling position of the device, shown by FIGURE 1.

The head 26 of the core-barrel is provided with a central bore in which a connecting element 31 is slidable, this element being coupled to the supporting rod 14 through a rotary connection 32 including ball-bearings.

A spring 33 surrounds the connecting element 31 and is compressed in the drilling position of the device (FIG- URE 1) between a shoulder 34 of the connecting element 31 and a bearing 35 of the core-barrel head 26.

An annular shoulder 36 at the bottom of the element 31 limits the upward sliding movement of this element, this shoulder coming into abutment against a lower hearing 37 of the core-barrel head 26. This annular shoulder 36 is adapted to obturate in the upper position of the piston 15 (FIG. 2) the lower apertures of the channels 28 this shoulder being then in abutment against the bear ing 37, which prevents in the coring position the circulation of flushing fluid inside the core-barrel, thereby preventing the washing-out of the sampled core by the flushing fluid.

The element 31, includes a recess 38 which opens out at its lower end at the top of the core-barrel 8 and is internally provided with a flap-valve or ball-valve 39 a1- lowing the fluid which fills the core-barrel 8 to escape as a core rises inside this core-barrel.

The recess 38 opens out through the aperture 40 into a groove 41 provided in the central bore of the head, in which the connecting element 31 is slidably mounted.

Outlet channels 42 provided in the core-barrel head 2.6

connect the annular groove 41 with the annular space included between the head 26 and the tubular body member 1.

The core-barrel head 26 will advantageously be profiled as illustrated, so as to form together with the internal wall of the tubular body member 1 an annular passage the axial section of which has the shape of a venturi, having its smallest cross-section at the level at which the channels 42 open out into this annular passage.

This arrangement results in the creation of a slight depression by the circulation of the flushing fluid through this passage, this depression being favorable to the upward displacement of the plug 9 and of the core inside the core-barrel 8, in the coring position of the device.

The device according to the invention also includes means for axially locking the core-barrel 8 in its lower or drilling position, the releasing of this locking means being controlled by an overpressure of the flushing fluid.

This locking means includes in the illustrated embodiment a piston or double plug 43 integral with a piston rod 55 and slidable within an axial bore 44 of the sup porting rod 14, this bore opening out at the top of the piston 15.

This piston bears on a spring 45 at the bottom of the bore 44 and cooperates with pawls 46 hinged within recesses which are provided at the periphery of the supporting rod 14 (only one of these pawls can be seen on the drawings).

When the piston 15 is in its lower position shown by FIGURE 1, the piston 43 is placed in its upper position in the bore 44 when the spring 45 is released, and in the absence of any sufficient pressure applied onto the piston 43, and this piston 43 then locks the pawls 46 in abutment against corresponding stops 47 provided at the lower part of the seat 17.

The core-barrel 8 is then maintained through the compression of the spring 33 in the lower or drilling position shown by FIGURE 1, the compressive force of the spring 33 being sufficient to provide by itself for the locking of the plug 9 on the drill crown 6 by means of the balls 10.

Under the action of the pressure rise in the feed of the flushing fluid as a result of the closure of the channels 23 through the balls 22, the piston 15 is first lowered over the small stroke which is left between the top of the sleeve 19 and the bottom of the piston 15 (FIG. 1) thereby compressing the springs 16 and 33, this stroke being however suflicient to free the pawls 46 from their abutment against their bearings 47.

Thereafter the pressure of the flushing fluid, by compressing the spring 45 causes the piston 43 to move downwardly within the bore 44, thereby releasing the pawls from their bearings and permitting the rocking movement of these pawls toward the axis of the device in the position shown by FIGURE 2.

A dog 51 hinged at 52 at the top of the piston 15 and including a bore 53 traversed by the rod 55 of the piston 43 provides for keeping this piston in its lower position illustrated by FIGURE 2 when the latter has reached this position, in order to avoid any risk of jamming of the pawls 46 during the upward movement of the piston toward its position of FIGURE 2.

To this end the dog 51 is associated with a return spring 54 tending to move its end 5.1a away from the upper side of the piston 15 by pivotal movement about 52 and the rod 55 is provided at its top with a part of reduced diameter forming an annular shoulder 56 at the level of its connection with the lower part of this rod. When this shoulder is lowered under the lower aperture of the bore 53 in the dog 51, the latter is slightly rocked and the shoulder 56 comes into abutment against the dog 51.

When the feed pressure of the flushing fluid is no longer applied, the piston 15 can rise under the action of the return spring 16 thereby raising the core-barrel 8 by means of the element 31 the annular shoulder 36 of which comes into contact with the lower bearing 37 of the core-barrel head 26.

When this piston 15 has reached its upper position illustrated by FIGURE 2, the end 51a of the dog 51 comes into abutment against the upper wall of the chamber 24 and the dog is thus brought back to its horizontal position. freeing the rod 55 which can again slide within the bore 53 of the dog 51, which will allow for the rising of this rod within the bore 44 during the resetting operation, i.e. durng the return of the device to the drilling position illustrated by FIGURE 1 (see below for this resetting operation).

The operation of the above described embodiment of the present invention will be as follows.

The device is lowered at the lower end of a drill pipe or string in its drilling position shown by FIGURE 1, without feeding the flushing flud, the pawls 46 being locked in abutment against their corresponding bearings 47.

When the device reaches the vicinity of the ground layer to be drilled this device is rotated before the circulation of flushing fluid is started.

Under these conditions the balls 22 moving aside under the action of the centrifugal force open a passage for the flushing fluid through the channels 23 of the piston .15.

The core-barrel 8 remains locked in its lower position (FIG. 1) the plug 9 being in this position fast with the drill crown 6 and it is then possible to drill on the full diameter of the latter.

The flushing fluid flows through the channels 23, 18, the annular space between the head 26 of the core-barrel 18, the internal wall of the tubular body member 1 and finally through the channels 7, irrigating the periphery of the cutting area.

In this position of the device (FIGURE 1), a part of the flushing fluid flows through the channels 28, the inner part of the tube 8, then through the channels 29, to the central part of the cutting area, thereby providing for the irrigation of this central part.

When the drill crown has reached the depth from which it is wished to collect samples or cores of the traversed geologic strata, the circulation of the fluid and then the rotation of the device are stopped.

The balls 22 fall then back to the bottom of the recesses 21 and obturate the channels 23.

The circulation of the flushing fluid is then set up again while the rotation of the device remains stopped, which produces a high pressure rise as a result of the obturation of the channels 23 of the piston 15.

The pressure of the flushing fluid first drives the piston 15 downwardly, thereby compressing the springs 16 and 33 and thus releases the pawls 46 from the hold-down force which they exerted. Thereafter the pressure of the flushing fluid pushes the piston 43 downwardly thereby comprising the spring 45 (FIG. 2), releasing the pawls 46 completely from their respective bearings and permitting their rocking motion toward the axis of the device, into the position illustrated by FIGURE 2.

At the moment the fluid circulation is stopped, the overpressure of the fluid is suppressed and the piston 15 can then rise back into the upper part of greater diameter of the chamber 24. During its rising motion this piston drives the core-barrel 8 into the upper position shown by FIGURE 2, by means of the annular shoulder 36 obturating at tht same time the channels 28.

When the circulation is set back, the flushing fluid can flow around the piston 15 with reduced pressure drop. It flows therefrom only around the core-barrel 8 as a result of the shoulder 36 resting on its seat.

In the position of FIGURE 2 the plug 9 is no longer locked at the lower part of the core-barrel 8 since the balls are released from the recesses .13 and this plug can then rise freely inside the core-barrel 8 as the core is forming. Due to the rotary coupling constituted by the ball-bearings 32, the core-barrel 8 is no longer fast in rotation with the drill crown in the position of FIG- URE 2 and thus covers without rotating the core cut out of the ground layer in which the sampling is effected.

In this upper part of the core-barrel 8, the section of passage between the bottom of this barrel and the annular shoulder 50 remains limited so as to avoid the risk of the core being washed out by the flushing fluid as this core penetrates into the core-barrel 8.

Core-catching devices placed at the lower part of the barrel 8 and which may be of any suitable type will permit to hold the core when the device is raised.

These core-catching devices may for example be constituted by articulated fingers 49 located at the periphery of the core-barrel.

After the device has been raised, the core housed in the core-barrel 8 will be extracted after having successively unscrewed the two threadings 4 and 27.

After the lower tubular element of the body member 1 has been removed, the device can be reset, i.e. brought back to its position of FIGURE 1 by applying on the annular shoulder 36, for example by bearing on the thread ing 4, a pull suflicient to compress the spring 16.

In order to keep the ring of the balls 10 locked against the plug 9 before placing back the lower tubular element 3, it will be advantageous to use a sleeve (not shown) surrounding the lower part of the tube 8, which will hold the balls 10, this sleeve coming into abutment against the internal shoulder 50 at the lower part of the element 3 and being then pushed upwardly so as to release the balls during the screwing of the tubular element 3 on the threading 4.

The housings or inclined grooves 13.provided in the internal wall of the drill crown 6 will preferably be located adjacent to one another as shown by FIGURE 1A, so that the balls always automatically find a seat.

The above-described embodiment is particularly designed for a drilling equipment having a bottom motor for driving the drill bit and a special characteristic of this drilling method or electro-drilling is used: the possibility to dissociate the rotation of the device and the circulation of the flushing fluid, i.e. the possibility to vary independently the speed of rotation and the flow rate of the flushing fluid.

Moreover there must be taken into consideration the low flow rate of drill mud which can be used with this drilling method in the cases of application which are involved, which leaves practically out the possibility of putting the device into its coring position by the only variation of the drill mud flow rate.

In the case of turbo-drilling, i.e. of the driving of the drill bit by means of a bottom turbine supplied with the drill mud or flushing fluid, the rotation and the circulation are functionally connected and the flow rates required by the turbine are distinctly greater than those which can be admitted by a coring device like the one shown by the FIGURES 1 and 2 for the irrigation of the drill bit.

Studies have shown that it was possible to keep in turbodrilling the coring device which had been designed for electro-drilling, by only modifying the upper part of this device so as to give this device a purely hydraulic control. The so-modified coring-device may then be driven in rotation by any underground motor or even from the ground surface, according to the rotary drilling method.

The releasable coring device according to the FIG- URES 3 to 7 is a device in accordance with the abovedescribed one, in which the device is put into its coring position by a succession of rises in the pressure of the drill mud or flushing fluid, these rises actuating an escapement device and simultaneously opening by-pass channels through which a part of the mud flow rate reaching the core-barrel head is directly discharged into the annular space between the tubular body member and the drilled well, so as to retain for the irrigation of the drill crown only the necessary flow rate, while the whole flow of flushing fluid is used during the previous drilling period.

In the FIGURES 3 and 7 only the upper part of the device has been shown since only this part has been modified while the lower part is identical to that of the embodiment illustrated by FIGURES l and 2.

Under these conditions the supporting rod 14 of the core-barrel has two positions:

(a) A lower position or drilling position (FIG. 3), in which the plug of the core-barrel is locked at the lower part of this barrel (corresponding to the position of FIG. 1) and (b) An upper position or coring position (FIG. in which this plug is unlocked and is freely slidable within the core-barrel (position of FIGURE 2).

The upper part of the device is housed in the body member I screwed through the threading 5 on a connecting piece for driving the device in rotation.

The assembly includes at its lower part a sleeve 19 which leaves a passage for the flushing fluid through apertures 18 and guides a spring 16. This sleeve is keyed on the supporting rod 14 whose lower part, housing a pawl 46 and a spring 45, is similar to that of the supporting rod 14 of the preceding embodiment.

The supporting rod is extended upwardly by a hollow piston 15 opening out at its upper part, this piston supporting the thrust of the spring 33 and letting a passage to the circulation of the flushing fluid through apertures 23a above which is located another gauged spring 57 which pushes upwardly an external sleeve 58 whose widened lower part 59 pentrates into the piston 15 and in the position of FIGURE 3 leaves for the circulation of flushing fluid only an annular space between this widened part 59 and the edge 60 of the upper aperture of the piston 15.

The sleeve 58 is fast in rotation with the supporting rod 14 while being axially slidable along the latter, supporting itself a sleeve 61 the axial stroke of which is limited by a stop 61a, but which can freely rotate about the rod 14. The sleeve 61 is provided at its top with a widened part 62.

The supporting rod 14 is terminated at its upper part by a widened head 63 provided with teeth distributed over two levels and constituting abutments for one or several teeth such as the tooth 64 integral with the widened part 62.

The sleeves 58 and 61 are furthermore connected by a spiral spring 65 which provides for a rotary thrust between the two sleeves, so as to press teeth like 64 against the teeth 66-66 distributed over the two levels at the periph cry of the widened head 63 of the supporting rod 14.

Inside the hollow rod 14 is located a push-rod 55 (identical to that of FIGURES 1 and 2) and at its upper part is placed a dog 51 hinged on an axis 52 and pushed upwardly by a spring 54 (FIGURE 7).

The rod 14 has an extension 67 on which is mounted a finned ring 68 the level of which is fixed by means of interchangeable adjusting rings 69 which may be placed either above or under the finned ring 68.

In the drilling position the flushing fluid flows from the bore 1a of the body member 1 through the central bore of a displaceable valve member 70 which is kept in position by a spring 71 so as to simultaneously obturate a plurality of channels 72 opening out in the external annular spa ce located between the body member 1 and the wall of the drilled well, through a protecting grid 73.

The location of the ring 68 with respect to the valve member 70 is so adjusted as to provide for slightly lifting this valve member during the rise of the supporting rod 14 when the device is put into its coring position.

The FIGURE 4 shows in a section by a plane at right angles to the axis of the device the locations of the tooth 64 integral with the widened part 62 of the sleeve 61 and those of the teeth or stops 66, 66 66 66 integral with the widened head of the supporting rod 14.

The FIGURE 5 shows, also in a section by a plane at right angles to the axis of the device, the spiral spring 65 which is connected at one of its ends with the sleeve 61 and at the other end with the external sleeve 58.

FIGURE 6 is a developed view of the circumference of the head 63, showing the displacement of the tooth 64 during the successive rises in the pressure of the flushing fluid.

As a result of the compression of the spring 57 and of the releasing thereof at the end of each pressure rise the tooth 64 is displaced between the two successive tooth levels 66 and 66 until the tooth 64 finally comes into abutment against the tooth 66 which locks the sleeve 62 in the upper position thereof, thereby limiting the section of the passage for the flushing fluid between the rim 60 and the part 59 to the apertures 23a.

FIGURE 7 shows the assembly in its coring position. The pawls 46 are tilted back to the axis of the device, the push-rod 55 is lowered thereby compressing the spring 71 and thus opening the channels 72 wherethrough is bypassed a part of the flushing fluid.

The device is operated as follows.

This device is lowered in its position shown by FIGURE 3, which corresponds to full hole drilling.

In this position the whole of the flushing fluid flows through the valve member 70, it pressure acting on the assembly 5861 causing the latter to move downwardly thereby compressing the spring 57 and opening between the part 59 and the rim 60 of the upper aperture of the piston 15 an annular passage for the flow of the flushing fluid to the drill bit, through the apertures 23a.

This axial downward sliding movement lowers the tooth 64 (FIG. 6) and the spring 65, rotating the sleeve 61, brings the tooth 64, which has just been released from the stop tooth 66 into abutment against the tooth 66, the tooth 64 following the way indicated by the arrows. The device is then in its drilling position.

When it is wished to start a coring operation, the circulation of the flushing fluid is Stopped. The spring 57 moves then the assembly 5861 upwardly and the tooth 64 is raised back to the level of the second stop tooth 66 against which this tooth 64 is pressed by the spring 65.

In order to lock the head 63 of the rod 14 in its position at the level of the upper teeth 66 66 66", corresponding to the coring position of the device, it will then be suflicient to rise the pressure of the flushing fluid as many times as necessary to bring the tooth 64 from its position in abutment against the tooth 66 to its final locking position against 66, the shape of this last tooth preventing the tooth 64 and hence the head 63 to move again downwardly as a result of a new pressure use.

In practice it will generally be suflicient to provide for three or four pressure rises followed by decompressions before the final locking in the coring position by the tooth 66 preventing the device from any inopportune releasing which could result of an accidental pressure variation.

When the tooth 64 has come into abutment against the stop tooth 66*, any new downward displacement of the assembly 5861 as a result of a new pressure rise is stopped by the part 74 of the tooth 66", which constitutes an axial abutment, the downward displacement of the supporting rod 14 being prevented by the powerful spring 33 and by the sleeve 19'.

The pressure exerted by the flushing fluid on the double piston 43 of the push-rod 55 causes the downward displacement of the push-rod 55, compressing the spring 45, which results in the pawl 46 tilting toward the axis of the device and the assembly 145861 rising under the action of the thrust exerted by the powerful spring 16, thereby releasing the central plug 9 from the drill crown or bit (as in the preceding embodiment) and opening a passage for the circulation of the flushing fluid between the piston 15 and the internal wall of the tubular body member 1.

The rise of the rod 14 simultaneously releases the rod 55 by rocking the dog 51 and raises the valve member 70 under the thrust of the finned ring 68.

The flow of the flushing fluid is thereby divided between the channels of the drill crown or bit at the lower part of the device and the outlet channels 72.

Thus in the coring position only a part of the total flow of the flushing fluid reaches the drill bit, the remainder of this flow being by-passed through the channels 72, which permits to use this device for turbodrilling by using in the coring position only that part of the total flow rate of the flushing fluid which is necessary for the irrigation of the drill crown.

The resetting of the device into its initial position will be performed on the ground surface, as in the case of the embodiment illustrated by FIGURES l and 2.

The resetting operation will however be slightly different from the one indicated for the preceding embodiment, in which it was sufiicient, after having unscrewed the lower element of the tubular body member so as to clear the rod 14, to exert a vertical downwardly directed thrust on this rod 14, bearing on the upper element of the tubular body member 1.

With the embodiment shown by FIGURES 3 to 7 it will be necessary to alternatively apply on the rod 14 downwardly directed pulls and rotate this rod so as to displace the tooth 64- along a way opposite the one indicated by the arrows on FIGURE 6, in order to reset the spring 65.

It will obviously be possible to combine this last embodiment with the preceding one, which amounts to provide at the lower part of the piston 15 of the device shown by FIGURES 3 and 7 channels or recesses 23 for housing balls 22, as shown on FIGURES 1 and 2.

This will provide a device the releasing of which requires a series of variations in the speed of rotation of the device and in the pressure of the flushing fluid.

We claim:

1. A coring device including a tubular body member provided with a drill crown at its lower end and housing a core-barrel, said tubular body member having means for connection with a driving mechanism and with a source of drilling fluid, a plug housed inside said corebarrel, releasable means operatively associated with said core-barrel for locking said plug at the lower part of the core-barrel, the lower part of said plug being provided with ground cutting elements, wherein said releasable locking means are adapted to be controlled through a plurality of elemental operations comprising at least a variation in the pressure of the drilling fluid.

2. Coring device in accordance with claim 1, wherein said core-barrel is axially displaceable inside said tubular body between a first position which corresponds to drilling and in which said plug is locked at the lower part of said core-barrel and a second position which corresponds to coring, in which said plug is released from said corebarrel and can slide within said core-barrel.

3. Coring device in accordance with claim 2, including means for locking said core-barrel in said drilling position, said locking means being adapted to be unlocked by the action of an overpressure of the drilling fluid.

4. Coring device in accordance with claim 3, including remotely controllable means, cooperating with said locking means, for increasing the resistance to the flowing of drilling fluid through said device, thereby producing an overpressure.

5. Coring device in accordance with claim -4, wherein said remotely controllable means includes means for reducing the flow section of the drilling fluid through said device, said reducing means being adapted to be actuated by the action of a predetermined series of variations in the pressure of the flushing fluid.

6. Coring device in accordance with claim 4, wherein said remotely controllable means includes a piston located in the flow of the drilling fluid and cooperating with said locking means, said piston having at least an internal channel for the drilling fluid, said section reducing means being associated with said channel.

7. Coring device in accordance with claim 5, wherein said means for reducing the flow section of the drilling fluid is adapted to be opened through a pressure rise in the drilling fluid and is associated with escapement means adapted to lock said section reducing means in a substantially closed position after a predetermined number of rises in the pressure of the drilling fluid.

8. Coring device in accordance with claim 1, including means for discharging a part of the flow of drilling fluid at a level located above the drill crown, said discharging means being adapted to be actuated in synchronism with the releasing of said releasable locking means.

9. Coring device in accordance with claim 4, wherein said core-barrel is integral with a piston which is provided with at least one channel for the passage of the drilling fluid and with a recess traversed from side to side by said channel, said recess having a bottom inclined with respect to the piston axis, said recess housing a ball adapted to close said channel for a predetermined range of rotation speeds of the device and to open said channel when said tubular body member is rotated at a speed outside said range of speeds.

10. Coring device in accordance with claim 2, wherein said locking means includes a plurality of balls housed within peripheral recesses which are provided at the lower part of said core-barrel, said balls simultaneously fitting into internal grooves provided at the lower part of said tubular body member and into recesses provided at the periphery of said plug.

11. Coring device in accordance with claim 2, including an elastic suspension for said core-barrel within said tubular body member.

12. Coring device in accordance with claim 11, wherein said suspension is provided with a rotary connection preventing the core-barrel to be rotated in the coring position of said device.

13. Coring device in accordance with claim 2, wherein said core-barrel is integral with said piston and wherein said tubular body member includes a part having an internal diameter substantially equal to that of said piston and a chamber having a greater diameter than said piston, said chamber housing completely said piston in only one of said two positions of the device, allowing then the drilling fluid to flow through the annular space between said piston and the internal wall of said chamber.

1 4. Coring device in accordance with claim 13, including sealing means for preventing the flow of drilling fluid around said piston when the latter penetrates into said tubular body member.

15. Coring device in accordance with claim 2, wherein said releasable locking means includes a rod terminated by a piston which is slidable within an axial bore provided in an element for supporting said core-barrel, said rod including means for drawing it back to a releasing position and cooperating with at least a pawl housed in a recess of the wall of said axial bore, a shoulder on said rod, said shoulder being adapted to lock said pawl against a corresponding seat integral with said tubular body member, said pawl being releasable by axial displacement of said rod.

16. Coring device in accordance with claim 2, wherein said drill crown and said plug are provided with irrigation channels, said core-barrel being provided with a head which is spaced from the internal wall of said tubular body member by an annular space for the flow of drilling fluid to the drill crown, said head including at least a passage for the drilling fluid to said channels of said plug and an axial bore in which is slidably mounted an element adapted to obturate said passage in said coring position of the device.

17. Coring device in accordance with claim 16, wherein said head of said core-barrel is provided with an outlet valve for the fluid filling said core-barrel in said coring position and channels for discharging said fluid into said annular space surrounding said core-barrel head, said core-barrel head being so profiled as to give said annular space an axial section having substantially the shape of an annular venturi which is provided with a depression Zone of reduced cross-section whereinto said discharge channels open.

18. A coring device including: a tubular body member provided with a drill crown at its lower end; means for connecting said tubular body member with a driving mechanism and with a source of drilling fluid; a corebarrel mounted in said tubular body member for axial displacement between a first drilling position and a second coring position; a plug slidably mounted in said core-barrel, said plug having ground cutting elements provided on the lower end thereof; pressure responsive means operatively associated with said core-barrel for locking said plug to the lower part thereof when said core-barrel is disposed at said drilling position and for releasing said plug therefrom when said core-barrel is disposed at said coring position; pressure responsive means for locking said core-barrel in said drilling position, said means being adapted to unlock said core-barrel in response to a predetermined overpressure of said drilling fluid; remotely controllable means cooperating with said core-barrel locking means for increasing the resistance to flow of the drilling fluid through said device, thereby producing said predetermined overpressure, said means including a piston disposed in the drilling fluid flow path, said piston having at least one internal channel for the drilling fluid and means cooperative with said internal channel and displaceable along the axis of said piston for reducing the flow section of the drilling fluid through the device; escapement means including a first element coaxial with said piston and fast with said section reducing means in axial displacement, a second element coaxial with said piston and integral therewith, elastic means associating said two elements for relative rotation, at least one stop means including a tooth member provided on said first element, a plurality of teeth members distributed according to a staggered arrangement over at least two levels of said second element, the distance between two successive teeth members and each of said levels being greater than the width of said tooth member provided on said first element, said section reducing means being laxially displaceable along the piston axis against the action of means for axial drawback between a first position wherein said tooth member of said first element is placed at a first of said two levels of said second element and is in abutment against a tooth member of said first level under the action of said elastic means, thereby stopping the rotation of said first element, and a second position wherein said tooth member of said first element is released from the teeth members of said first level and comes into abutment against a tooth member of said second level, under the action of said elastic means, one of said teeth members of said second element having a shape adapted to lock said tooth member of said first element in said position thereof.

19. A coring device including a tubular body member provided with a drill crown at its lower end; means for connecting said tubular body member with a driving mechanism and with a source of drilling fluid; a corebarrel mounted in said tubular body member for axial displacement between a first drilling position and a second coring position; plug means slidably mounted in said core-barrel, said plug means having ground cutting elements provided on the lower end thereof; pressure responsive means operatively associated with said corebarrel for locking said plug means to the lower part thereof when said core-barrel is disposed at said drilling position and for releasing said plug means when said corebarrel is disposed at said coring position; means for discharging a part of the drilling fluid from said device at a position disposed above said drill crown, said discharging means being adapted for synchronous actuation with said pressure responsive locking means to effect a synchronous discharge of the drilling fluid from said device and the release of said plug means, said discharging means including at least one by-pass channel and a valve member cooperating therewith in response to the axial displacement of said core-barrel, said valve member being adapted to open said by-pass channel exclusively when said core-barrel is disposed at said coring position.

References Cited UNITED STATES PATENTS 1,542,172 6/1925 Reed l245 2,574,717 11/1951 Stokes l75245 2,633,336 3/1953 Stokes l75245 2,862,691 12/1958 Cochran l75245 X 2,865,608 12/1958 McKenna 245 X NLLE C. BYERS, JR., Primary Examiner 

